Telephone system



Nov. 9,1937. w. w. CARPENTER ET AL 2,098,274

TELEPHONE SYSTEM Filed Jan. 29, 1937 .ww CARPENTER 0. MYERS A T TORNE' V Patented Nov. 9, 1937 PATENT OFFICE TELEPHONE SYSTEM Warren W. Carpenter,

Garden City, and Oscar Myers, Brooklyn, N. Y., assignors to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application January 29, 1937, Serial No. 122,973

9 Claims.

This invention relates to telephone systems and has for its object to increase the efficiency of operation of such systems.

In the cross-bar system, the operation of testing the wanted line is performed by common control apparatus known as a. marker which is connected with the line through a link including a plurality of conductors, a set of relays for connecting any marker with the conductors and a set of relays for connecting the conductors with a group of lines, one relay of each set being perated for each call. In the marker these test conductors are connected to a set of test relays for determining whether the called line is busy or idle. If one of the conductors in the link becomes grounded falsely, each time that a connection is attempted the corresponding line will appear to be busy. In order to test these conductors for a. false ground,.it is necessary to delay the connection of the conductors with the line and therefore increase the holding time of the marker.

In accordance with the present invention, means is provided for testing the conductors of the link by associating conductor testing means with the normal line testing means and delaying the connection of the conductors with the lines during the test. In order to avoiddelaying calls due to the increase in marker holding time, means is provided to prevent the test being performed when the marker is reseized within a predetermined length of time after release.

The invention Will be more clearly understood from the consideration of the following description read in connection with the drawing, which shows a portion of a marker and within the rectangle at the bottom a portion of a link or line choice connector including the conductors to be tested. A large part of the disclosure has been selected from the drawing accompanying the application of W. W. Carpenter, Serial No. 68,262, filed March 11, 1936, and where possible the same reference numerals have been employed. Reference is hereby made to that application for a description of the system as a whole.

When a terminating call arrives at an ofiice employing cross-bar type switches, a terminating sender is seized and the line number is transmitted from the originating office to this sender. The sender then connects with a terminating marker to which it transfers the recorded number. The marker translates the number into a set of three cross-connections individual to a group of twenty lines including the wanted line.

Over one of these cross-connections it seizes a line choice connector, operating marker connecting relay 3200. It then operates a hundred-block 'relay 3| 04 and thereafter a twenty-block relay 3| 08. Each twenty-block relay has two armatures for each of twenty lines, one closing the sleeve or test circuit and the other a class or position identifying circuit. These twenty pairs of circuits also extend over the contacts of the marker connecting relay 3200, and it is the conductors I00, IOII, etc., to be included in the test circuits between the armatures of relay 3200 and the contacts of relay 3I08 which are tested in the present arrangement.

During the progress of a normal call, relay I02 is operated over conductor 5658 as soon as the marker connector connects the marker and sender together. As soon as the registration and translation are completed, three circuits are prepared, one to a preference chain in the line choice connector, one for a marker twenty-block relay such as relay 5308, and one for a connector hundred-block relay such as relay 3I04. Belay 5308 operates immediately, in turn operating relay 8302. As soon as the line choice connector is available, which may be immediately, the preference relay operates, in turn operating relay 3200. With relay 3200 operated, the circuit of relay 3I04 is completed, followed, if no test is to be made, by relay 3I08, whose circuit may be traced from battery through the winding of relay 3W8,- front contact of relay 3I0 I, front contact of relay 3200, front contact of relay 6302, front contact of relay 5308, back contact of relay 5309, winding of relay I03, middle back contact of relay I04, back contacts of relays I05 and I06, outer front contact of relay I02 to ground. With relay 3I08 operated, one line test circuit extends, for example, from conductor I229 over a front contact of relay 3I08, conductor IOI, front contact of relay 3200, back contacts of relays 45I9 and 4525, winding of test relay 52I9, inner back contact of relay I04 to battery. Relay 52I9 operates from ground on conductor I229 to indicate that the line is busy. Relay 5200 makes a similar test of the line to which it is connected and similar relays test the remainder of the group of twenty lines identified by the operation of relays 3200, SIM and 3I08.

As above indicated, if one of the conductors I00, IOI, etc. becomes grounded falsely, each time that a group of lines is tested the corresponding line will appear busy. Therefore, when possible, as will appear hereinafter, the operation of relay 3I08 is delayed long enough to make a test of these conductors. Relay )2 in operating closes a circuit over the back contacts of relays It? and 4835 to the winding of relay H14 and battery. Relay I04 locks under the control of relay 4835, disconnects the windings of relays 520i 52l9, etc., from battery and connects them in multiple over the back contact of relay it! to the winding of relay 06 and battery. A false ground on one of the conductors I03, itl, eto., operates relay I66, which locks through resistance I 09 to ground at the back contact of relay i H). Relay I06 opens the circuit of relay 3588 and operates trouble release relay 5828 to cause a record of the trouble to be made. If no trouble appears, the operation of relay 3200 in turn operates relay i835. Relay 4335 opens the locking'circuit of relay Hi4, which closes its back contacts after an interval, completing the circuit of relay (H08 and permitting the call to proceed.

In order to obviate this delay when the traffic is heavy, a timing circuit controls the operation of relay I04. Relay 4824 is operated in the chain circuit closed for checking the registering leads connecting sender and marker, and locks under the control of relay I22. Relay 4824 in turn operates relays Ill and lfi'l, these relays remaining operated until the release of the marker connector releases relay Hi2. Relays HI and H31 release slowly to measure off a definite interval of time. As long as relay Iii? holds its contact open, relay I04 cannot operate. If the calls are ar riving so rapidly that the marker is reseized before relays Ill and I0! can release, relay m4 does not operate and no test is made of the sleeve link conductors I00 and HM until the traific slows.

Relays 39!, 3992, 3904, etc., are operated under special conditions, for example, when a call is to be routed to an intercept operator. When relay I04 applies the test above described to the sleeve linkage, a similar test is applied to these relays. They are connected over the outer front contact of relay I04, back contact of relay 3am to the winding of relay Hi5, which performs the same functions as relay I06.

A similar test is applied at will under the control of key H2 to the linkage in the class indi cating circuit. With key H2 operated, relay H3 is operated, opening the direct battery supply to relays 5220 to 5239 and closing their windings through to the winding of relay I55, which performs the same functions for these circuits that it does for the sleeve circuits. However, this test is only applied during general tests of the marker.

What is claimed is:

1. In a telephone system, a control device, means for seizing said device, testing means in a said device, timing means started when said device is released and means for preventing the operation of said testing means if said device is reseized before said timing means completes its operation.

2. In a telephone system, a control device, means for successively seizing said control device, a plurality of groups of lines, means including a plurality of conductors for connecting said control device with one of said groups of lines when seized, means for testing said conductors and means depending upon the frequency of successive seizures for determining whether said test shall be performed.

3. In a telephone system, a control device, means for successively seizing said control device, a plurality of groups'of lines, means including a plurality of conductors for connecting said control device with one of said groups of lines when seized, means for testing said conductors, timing means started by the release of said control device and means for pre en-ting said test if said device is reseized within a predetermined length of time.

4. In a telephone system, a control device, a plurality of groups of lines, a plurality of conductors, first connecting means for connecting said control device with said conductors, second connecting means for connecting said conductors with one of said groups of lines, means in said device for testing said lines over said conductors, means for testing said conductors, means for associating said conductor testing means with said line testing means and means for preventing the operation of said second connecting means during said association.

5. In a telephone system, a control device, a plurality of groups oflines, a plurality of conductors, first connecting means for connecting said control device with said conductors, second connecting means for connecting said conductors with one of said groups of lines, means for testing said conductors, and means for preventing the operation of said second connecting means during said test.

6. In a telephone system, a control device, a piurality of groups of lines, a plurality of conductors, first connecting means for connecting said control device with said conductors, second connecting means for connecting said conductors with one of said groups of lines, means for testing said conductors, means for delaying the operation of said second connecting means during said test, timing means started when said device is released, and means for canceling said delay if said device is reseized before said timing means completes its operation.

'7. In a telephone system, a control device, means for successively seizing said control device, a plurality of groups of lines, a plurality of conductors, first connecting means for connecting said control device with said conductors, second connecting means for connecting said conductors with one of said groups of lines, means for testing said conductors, means for preventing the operation of said second connecting means during said test, and means depending upon the frequency or" successive seizures for determining whether said conductor test shall be performed.

8. In a telephone system, a control device, means for seizing said device, a plurality of groups of lines, a plurality of conductors, first connecting means for connecting said control device with said conductors, second connecting means for connecting said conductors with one of said groups of lines, means in said device for testing said lines over said conductors, means for testing said conductors, means for associating said conductor testing means with said line testing means, means for preventing the operation of said second connecting means during said association, timing means started when said device isreleased, and means for preventing the operation of said conductor testing means if said device is reseized before said timing means completes its operation.

9. In a telephone system, a control device, means for successively seizing said control device, a plurality of groups of lines, a plurality of conductors, first connecting means for connecting said control device with said conductors, second connecting means for connecting said conductors with one of said groups of lines, means in said device for testing said lines over said conductors, means for testing said conductors, means for associating said conductor testing means with said line testing means, means for preventing the operation of said second connecting means during said association, and means depending upon the frequency of successive seizures for determining whether said conductor test shall be performed.

WARREN W. CARPENTER. OSCAR MYERS. 

